1 files changed, 38 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Array/prototype/flat/proxy-access-count.js b/js/src/tests/test262/built-ins/Array/prototype/flat/proxy-access-count.js
new file mode 100644
index 0000000000..3100f4ecc8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Array/prototype/flat/proxy-access-count.js
@@ -0,0 +1,38 @@
+// Copyright (C) 2018 Richard Lawrence. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.flat
+description: >
+  properties are accessed correct number of times by .flat
+info: |
+  Array.prototype.flat( [ depth ] )
+
+  ...
+  6. Perform ? FlattenIntoArray(A, O, sourceLen, 0, depthNum).
+
+  FlattenIntoArray (target, source, sourceLen, start, depth [ , mapperFunction, thisArg ])
+
+  3. Repeat, while sourceIndex < sourceLen
+    a. Let P be ! ToString(sourceIndex).
+    b. Let exists be ? HasProperty(source, P).
+    c. If exists is true, then
+      i. Let element be ? Get(source, P).
+features: [Array.prototype.flat]
+includes: [compareArray.js]
+---*/
+
+const getCalls = [], hasCalls = [];
+const handler = {
+  get : function (t, p, r) { getCalls.push(p); return Reflect.get(t, p, r); },
+  has : function (t, p, r) { hasCalls.push(p); return Reflect.has(t, p, r); }
+}
+
+const tier2 = new Proxy([4, 3], handler);
+const tier1 = new Proxy([2, [3, [4, 2], 2], 5, tier2, 6], handler);
+
+Array.prototype.flat.call(tier1, 3);
+
+assert.compareArray(getCalls, ["length", "constructor", "0", "1", "2", "3", "length", "0", "1", "4"], 'The value of getCalls is expected to be ["length", "constructor", "0", "1", "2", "3", "length", "0", "1", "4"]');
+assert.compareArray(hasCalls, ["0", "1", "2", "3", "0", "1", "4"], 'The value of hasCalls is expected to be ["0", "1", "2", "3", "0", "1", "4"]');
+
+reportCompare(0, 0);